Risk and protective factors for suicide in cancer patients were assessed by comparing individual who died by suicide or natural causes on several dependent measures. Statistical analyses were conducted with SPSS version 22.0. Chi-square analyses were used to examine categorical variables such as demographic variables and cancer characteristics. Independent t-tests were used to examine continuous variables such as age at TOD. Analyses revealed several trends that did not reach statistical significance.

Cancer patients who died by suicide and natural causes were similar on demographic features (see Table 1). No significant between-group differences were observed in the average age, race, gender, or marital status of the decedents. The mean age of suicide decedents was 66.67 (SD = 15.43) and the mean age of cancer patients who died by natural causes was 59.33 (SD = 7.30; ns).  Both groups were primarily composed of subjects who were white, male, married, and had children.

Cancer characteristics were compared across the groups regarding when the subjects were first diagnosed with cancer, recent hospitalization due to medical causes, and current chemotherapy treatment (Table 2). No significant between-group differences were observed based on timing of the first cancer diagnosis within the past 6 months (χ²(1, 18) = 1.29, ns). No significant between-group differences were observed based on the number of recent hospitalizations in the suicide decedent and natural death subsamples (χ²(1, 18) = 1.29, ns). The suicide decedent group and the natural death group did not significantly differ on rates of current chemotherapy treatment (χ²(1, 18) = 1.06, ns). No between-group differences were observed in rates of additional medical illnesses at time of death between the suicide group and natural death group (χ²(1, 18) = 1.06, ns). Suicide decedents and cancer decedents showed similar levels of pain at time of death (χ²(1, 18) = 1.29, ns) and utilized similar amounts of pain medication (χ²(1, 18) = 0, ns). The medical or natural death decedents had a higher rate of financial burden than the suicide decedents that approached statistical significance (χ² (1, 18) = 3.60, p < .06).

Cancer patients who died by suicide or natural causes showed similar levels of social support. There were no significant between-group differences in family support (χ²(1, 18) = 1.00, ns). In both groups, over 50% of subjects had evidence of familial support. There were no significant between-group differences in support by friends (χ²(1, 18) = 0.0, ns). Both groups evidenced low rates of support by friends.

There were no significant differences in psychiatric morbidity between cancer patients who died by suicide or natural/medical causes (see Table 3). Suicide decedents displayed higher rates of depressive disorders (major depressive disorder, persistent depressive disorder, adjustment disorder with depressed mood, or depression not otherwise specified) that trended toward significance (χ²(1, 18) = 3.60, p < .06). Suicide and natural death decedents showed similar levels of chronic depression (χ²(1, 18) = 1.00, ns). There were no significant between-group differences in rates of recurrent depression (χ² (1, 18) = 2.49, ns). No between-group differences were observed for diagnoses of alcohol use disorders (χ² (1, 18) = 2.10, ns) or psychoactive substance use disorders (χ² (1, 18) = 2.49, ns). There were similar rates of psychotic disorders in the suicide and natural death groups (χ² (1, 18) = 1.29, ns). Cancer patients who died by suicide or natural causes showed similar rates of diagnoses of anxiety disorders at time of death (χ² (1, 18) = 0.28, ns).

The aim of the study was to evaluate cancer patients who died by medical or natural causes or by suicide, and to identify protective and risk factors for suicide in those who have been diagnosed with cancer. Unlike previous studies that examined suicidality in cancer patients, our study did not find significant differences between patients with a cancer diagnosis at TOD who died by suicide and those who died by natural or medical causes.5,7 It is often assumed that all populations that display suicidality exhibit similar characteristics. However, previous studies examining individuals who attempt suicide and individuals who complete suicide have concluded that these populations are significantly different in many aspects including demographic characteristics and method of suicide.22 The results of this study highlight the importance of differentiating individuals who have suicidal ideation, suicidal behaviors, and those who die by suicide.

There were no statistically significant differences between our two cohorts, but there were several trends in the data that approached significance. Results suggest that a diagnosis of a depressive disorder (Major depressive disorder, persistent depressive disorder, adjustment disorder with depressed mood, or depression not otherwise specified) at TOD may be a signal for increased risk of completed suicide following a diagnosis of cancer. This may be a clinically useful finding that health-care providers should take into account when delivering cancer diagnosis to older adults. Medical providers could make use of quick depression screeners to assess need for further evaluation or referral to mental health providers. Specifically, with the knowledge that a history of depression could hasten the desire for death among patients with terminal cancer, heavy emphasis on the importance of maintaining one s mental health throughout the course of treatment or into the next stages of the disease must be conveyed to the patient. Recurrent depression was not found to be significantly different between both groups. Further research could explore if new onsets of depressive disorders or depression severity presents as a risk factor for suicide in cancer patients.

Another finding that approached significance was a higher likelihood of having a financial burden due to medical bills in the natural death group. Financial burden as a protective factor seems counterintuitive as financial difficulties are associated with suicide risk.26 One possibility that could account for this trend is that, most subjects in both groups had evidence of other medical conditions. It is unclear as to whether the financial burden is directly related to costs of cancer treatment or whether they are related to other medical conditions. Other potential reasons for this trend is that there is a possibility that individuals who died of medical or natural causes could have had more contact with medical or mental health providers or displayed a higher rate of help seeking behaviors. Future research could investigate the role of help seeking behavior from medical and mental health providers in cancer patients who die by suicide or display suicidal behaviors.

Psychological autopsies of suicide decedents and natural deaths require consent and participation from next-of-kin who provide data while mourning. Suicide, especially among cancer patients, is a rare event. The present study was limited because of the small sample size. The sample size was reduced further when data from decedents who were not known to be aware of their cancer diagnosis were removed from the study. Statistical power is an important factor when attempting to determine statistical differences between populations. Power is the probability that a test will correctly reject the null hypothesis indicated a significant difference. With our current sample size (N = 18) the power (0.56) is insufficient to reject the null hypothesis. For a sufficient power (0.80) the estimated sample size (31.40) would need to be increased approximately 57%. Considering the current level of power in our analyses, results approaching significance are promising. Further research with larger sample sizes are needed to evaluate risk and protective factors in individuals who die by suicide.

Findings shed light on characteristics that may increase suicide risk in cancer patients. Adults who are diagnosed with cancer may experience similar struggles at similar rates, with the emotional burden of the cancer diagnosis being especially prominent among both groups. It is important for clinicians and physicians to be acutely aware of the risk of suicidal behavior among the terminally ill, providing the resources and therapeutic support that is available for battling severe sickness and psychological distress.